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bradmason509 avatar image
bradmason509 asked

BMV 712 Temp sensor and Lynx Distributor?

The wiring diagram shows to hook the power directly to the battery using the temperature on the BMV 71. I want to wire it directly to my Lynx Distributor so it can be cut off and there won't be a parasitic drain if I don't use my van for weeks. Is that ok? The distributor will be in close proximity to the batteries, so the temperature should be close.


Temperature Sensor
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2 Answers
wkirby avatar image
wkirby answered ·

In principle, you could mount the temperature sensor in the Lynx Distributor but then you will not be measuring the actual battery Voltage. Instead you will have inaccuracies because you will be measuring the Voltage drop over the cables when high currents are flowing.
Secondly you would not be measuring the actual battery temperature - obviously.
The purpose of the device is to monitor the battery, if it is disconnected then it's no longer doing its job anymore.

The energy consumption of the BMV-712 is less than 1mA if the back-light is off which is probably less than the self discharge of the battery its self.

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bradmason509 avatar image bradmason509 commented ·
I didn’t think it would make a difference in the reading from the shunt.
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wkirby avatar image wkirby ♦♦ bradmason509 commented ·
The current reading through the shunt will be unaffected but the Voltage reading will be different from the actual battery terminal Voltage if it is measured somewhere else in the circuit. The only time it will be accurate is when the current is 0A.
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Kevin Windrem avatar image
Kevin Windrem answered ·

Another reason to NOT disconnect the BMV is it will reset the state of charge reading requiring a full battery recharge before it will provide SOC numbers. You can set the BMV to reset to 100% but that's generally incorrect.

1 mA of draw on a 100 AH battery will drop the battery 10% SOC in 10,000 hours or 13.8 months.

Just leave it connected.

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